The present invention relates generally to the field of catheters. More specifically, the present invention relates to catheters which are adapted to be inserted into the urethral lumen to alleviate obstructive prostatism, a condition quite common in males over the age of 50.
The prostate is a somewhat pear-shaped gland that extends around the urethral lumen from the neck of the bladder to the pelvic floor. Because of the close relationship of the prostate to the urethra, enlargement of the prostate, usually referred to as hypertrophy or hyperplasia, may fairly quickly obstruct the urethra, particularly if the hyperplasia occurs close to the lumen. Such an obstruction inhibits normal micturition, which causes an accumulation of urine in the bladder.
The surgical treatment of hyperplasia of the prostate gland has been a routine procedure in the operating room for many years. One method of surgical treatment is open prostatectomy whereby an incision is made to expose the enlarged prostate gland and remove the hypertrophied tissue under direct vision. Another method of treating obstructive prostatism is a technique known as transurethral resection. In this procedure, an instrument called a resectoscope is placed into the external opening of the urethra and an electrosurgical loop is used to carve away sections of the prostate gland from within the prostatic urethra under endoscopic vision.
The technique of transurethral resection offers many benefits to the patient as compared to open prostatectomy. Using this technique, the trained urologist can remove the hypertrophied prostate with less patient discomfort, a shorter hospital stay and lower rates of mortality and morbidity. Over 333,000 patients underwent this procedure in the United States in 1985, with an average hospital stay of six days. Notwithstanding the significant improvement in patient care resulting from the widespread application of transurethral resection, there remains a need for a less invasive method of treating the symptoms of prostate disease.
One of the earliest methods of relieving acute urinary retention, a symptom associated with prostate disease, was the placement of a catheter through the external urethral opening into the bladder, thereby allowing the outflow of urine from the bladder by way of the catheter lumen. These urinary catheters typically employ a balloon at the tip which, when inflated, prevents the expulsion of the catheter from the body. However, due to problems of infection, interference with sexual activity, and maintenance involved with such catheters, they are generally unacceptable for long term treatment of micturition problems.
U.S. Pat. No. 4,432,757 to Davis, Jr. teaches the use of an indwelling urethral catheter assembly, having a Foley-type balloon disposed near the distal end thereof and a substantially non-compliant balloon lead shaft proximate to the Foley-type balloon. The device is adapted to be inserted through the urethra up into the bladder. The Foley-type balloon and the balloon lead shaft are then inflated, although the balloon lead shaft remains relatively non-compliant and therefore does not expand appreciably. Gentle traction is then applied to a catheter sleeve head to sever the sleeve from the remainder of the catheter, leaving the balloon lead shaft in position within the urethra.
Another method of treating hypertrophy of the prostate gland without the need for surgery has been to inject medications into the prostate gland by means of a catheter. Such a device is disclosed in U.S. Pat. No. 550,238 to Allen, wherein two balloons are disposed along two sections of a catheter, and inflated to isolate an area within the urethra prior to the injection of the medication. However, these injections are frequently ineffective as the prostate gland exhibits only a limited ability to absorb the injected antibiotics, and proper positioning and retaining of the catheter with respect to the affected area is extremely difficult.
A substantial improvement in an apparatus and corresponding method of treatment for obstructive prostatic hypertrophy is disclosed in Klein, U.S. Pat. No. 4,660,560. In Klein's method, a calibrating catheter is used to measure the distance between the neck of the bladder and the bottom of the prostate gland. A dilatation catheter, having an annular balloon with a length equivalent to the measured length, and a Foley-type balloon at the distal end thereof is then inserted into the urethra until the Foley-type balloon is within the bladder. The Foley balloon is then inflated in the bladder and is used to position the dilatation balloon in the prostrate. The latter balloon is then inflated, to force the prostate away from the urethral lumen. Use of the Klein catheter can effectively eliminate uncertainty regarding positioning of the upper (distal) end of the dilatation balloon, thereby significantly facilitating the treatment of prostatic hypertrophy.
In practicing the Klein method, after the calibration catheter is used to measure the length of the affected prostate, it is withdrawn from the urethra, and the dilatation catheter is then inserted. Proper insertion of the dilatation catheter is crucial, as stretching of the external urethral sphincter muscle, which lies just below the prostate, could cause incontinence. Although some means of visualizing placement of the proximal end of the dilatation balloon is therefore desirable, the catheter is too large to fit through a conventional cystoscope sheath. Moreover, bleeding, which is common during such a procedure, not infrequently obscures the field of view of a cystoscope lens, making it useless.
Accordingly, in practicing the method of the Klein patent, there is a need for a method and apparatus to permit effective and sure positioning of the proximal end of the dilatation balloon with respect to the external urethral sphincter. There is a particular need to permit visualization of the balloon placement in vivo during the course of the surgical procedure.